Re: How do i pick out a transformer?

The transformer will yeild an output that has a relatinship to the
input by the ratio of input windings to output windings.

not that you need to count windings, but the ratio is all you need.

since it outputs AC, you need to rectifiy it. the diodes will drop
about 1.2 volts

So your staring AC is changed in the transformer to your new voltage,
less about 1.2 volts.

since you are now converted to DC, the line will have a lot of noise
from the AC wave from, so you add a filter capacitor.

when you add that, you no longer measure RMS, but the cap yields the
total DC voltage and that is 1.414 times the rectified AC.

so your 48 volt output would be 46.8 volts time 1.414 to yeild 66.175
volts DC.

change the numbers to figure out what transformers are avalable in
the ranges you need.

Dave





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "twoextrememachine"
<twoextrememachine@y...> wrote:

> I'm finally ready to build a power supply which doesn't appear to

be

> to difficult. But, I am having issues picking out a toroid
> transformer. I know i have approx 110VAC or the wall socket, and I
> need 100VDC and 20amps, which is the max for a rutex drive of

course

> slightly underpowering my motors which i feel fine about. I'd

rather

> under juice them than have the ability to over juice them. So when

I

> look at transformers what should I look for, to get the desired
> output? I can handle the rest with the bridge rectifier and
> capacitor.